During September rehearsals for The Shadow King, the new production of King Lear by Melbourne’s Malthouse Theatre, Jimi Bani, who plays Edmund, ran through his final, bitter scene with Jada Alberts and Natasha Wanganeen as Lear’s dog-hearted daughters Goneril and Regan. The characters fought and yelled as the sisters realised Edmund had lied to them both. In quick succession, Regan stumbled to the ground, Edmund kicked her and then he started to run after Goneril, who had left the stage. The scene was violent and alive, but it wasn’t quite there. Michael Kantor, the director, started asking questions. Where should Jada throw the bag? How does Natasha fall? What about when Regan is dead and Edmund turns to run after Goneril? Kantor encouraged Bani to slow that moment down. A few minutes earlier, Edmund was tempted to leave and make his future with Goneril, but all his schemes have come undone. He’s going to kill her now, Kantor said. Bani asked him, “Do you want to see him make the decision?”

Bani, like the rest of the cast, is indigenous, and throughout the play he speaks in Kala Lagaw Ya, Yumpla Tok and English. Other actors also speak Gupapuyngu, Nunggubuyu and Kriol (the Top End creole). It’s a revelation for audiences who either haven’t heard Aboriginal languages or have heard them only in the context of museums or documentaries. Many non-indigenous Australians – especially those in the south – assume that Australian languages are going extinct. Although the loss has been extraordinary, there are pockets around the country where the languages refuse to die. A 2012 government report into the state of indigenous languages found that they are vital to Aboriginal people’s health and wellbeing.

In 2010, Michael Kantor went to Katherine, in the Northern Territory, to meet the actor Tom E Lewis. He wanted to ask Lewis, who would go on to play Lear in the current production, what would happen if you introduced Shakespeare to the Dreamtime. Kantor and Lewis spoke about a handful of plays, but it was King Lear that really resonated. For Lewis, its themes of land and ownership and meaning and misunderstanding echoed modern indigenous conflict around land rights and mining.

In 2011, Kantor and Lewis spent a week at the Malthouse Theatre with six indigenous actors to see if a translation of Lear might work. The actors brought with them not just different languages but a different relationship to language. There are rules of ownership, Bani tells me. It’s not like French. You can’t go to school and learn it. “There’s a lot of permission, a lot of cultural protocol that you’ve got to set up, especially in business in indigenous culture,” he explains. “For us to be safe as indigenous people, you don’t want to offend anyone, and you don’t want to talk other [indigenous peoples’] languages.”

As Edmund, Bani displays a malevolent grandeur, but in person he is sincere and sweet. He was born in the Torres Strait and is the eldest son of Dimple Bani, the chief of the Wagadagam. His totem is the crocodile, and his constellation is the shark. He grew up speaking the local creole, Yumpla Tok. “Yumpla Tok means you and me, us, talk.” Bani also speaks Kala Lagaw Ya, his father’s language, and during the play’s development he would phone his father to find translations.

In one of the play’s most powerful moments, Regan screams “Half blood!” at Edmund. It’s the curse that trails him. He is illegitimate, a bastard. Edmund responds, “Gathaw Waaru? Gathaw Waaru? Always, always Gathaw Waaru!” It’s a shallow-water turtle, Bani says. “As opposed to a deep-water turtle. You know what I mean? That’s insulting. It’s like, ‘You keep in the shallow, you don’t know how to dive in the deep, you’d be scared.’ That’s basically ‘the bastard’ in our life.”

At first, says Kantor, they rendered a lot of the original play into Kriol, but over time they pulled back and mixed in more English. Now, the languages run through the play in different ways. When Lear rages at Cordelia (Rarriwuy Hick), Lewis moves so fluidly from Kriol into English and back again that it’s hard to tell where the seams are, yet his meaning is unmistakable. Frances Djulibing, as Gloucester, often says a phrase in Gupapuyngu and then repeats it in English.

It feels like a natural emphasis but works like a language lesson. Kamahi Djordan King, the Fool, addresses the audience in Kriol and Aboriginal English, “It bin happening in this community la.” Of Edmund, he says, “He nogudwan thatun,” and he asks, “You sabi who this is?” The effect is extraordinary. Most people will understand exactly what he’s saying.

“That was the great discovery of the translation,” Kantor says. The mix of the familiar and the unfamiliar provokes a kind of heightened state, as might a fragment of a forgotten poem or a half-recognised face, or, in fact, as might the original Shakespeare to a speaker of modern English.

Shakespeare’s plays have been translated into hundreds of languages, including Yiddish, Urdu and Mandarin, but never before into an Australian one. The Shadow King will tour Sydney, Perth and Adelaide in early 2014. In Melbourne, where the play sold out its season in October, the opening night audience sat rapt until the awful scene was upon them. Regan lay bloody on the ground, Goneril had left, and Edmund stood looking after her. Without saying anything, he made his terrible decision. It passed across his face, at first slowly and then really, really fast. By the time he started running, everyone knew what he was going to do. Sometimes, you don’t need words at all.